1. Field of the Invention
The present invention relates to a method and system for inspecting the occurrence of a foreign matter or defect in a device manufacturing process, wherein a foreign matter existent on a thin-film substrate, a semiconductor substrate, or a photomask, or a defect occurring in circuit patterns is detected in the course of manufacturing a semiconductor chip or a liquid crystal product, and the detected foreign matter or defect is analyzed in order to take measures.
2. Description of the Related Art
In a semiconductor manufacturing process, the presence of a foreign matter on a semiconductor substrate (wafer) causes a defective such as imperfect insulation of wiring or a short circuit thereof. Furthermore, due to the trend of semiconductor devices to a more and more microscopic structure, a more microscopic foreign mater brings about imperfect insulation of a capacitor or destruction of a gate oxide film. The foreign matters are mixed in various states because of various causes. Namely, the foreign matters may be produced by a movable unit included in transportation equipment or a human body, produced in processing equipment due to reaction of a process gas or the like, or originally mixed in a chemical agent or material.
Likewise, in a process of manufacturing a liquid crystal display device, if a defective pattern is produced in a work due to a foreign matter, the work cannot be adopted as a display device. The same applies to a manufacturing process of a printed circuit board. The mixture of a foreign matter causes a short circuit or a defective connection in patterns. Under such a background, in the case of semiconductor manufacturing, a plurality of foreign matter inspection systems may be disposed relative to each production line. Thus, the presence of a foreign matter is discovered in the earliest possible stage and fed back to the manufacturing process, whereby a yield in manufacturing of a semiconductor device is improved.
As one of techniques for detecting a foreign matter on a semiconductor substrate, Japanese Unexamined Patent Publication No. 62-89336 (Prior Art 1) has disclosed a method capable of highly sensitively and highly reliably inspecting the presence of a foreign matter and the occurrence of a defect by discarding false or misleading information acquired from patterns. According to the method, light scattered from a foreign matter, which adheres to a semiconductor substrate, after laser light is irradiated to the semiconductor substrate is detected, and then compared with a result of inspection conducted on a semiconductor substrate of the same type that has been inspected immediately previously. Moreover, as disclosed in Japanese Unexamined Patent Publication No. 63-135848 (Prior Art 2), a method is known in which light scattered from a foreign matter, which adheres to a semiconductor substrate, after laser light is irradiated to the semiconductor substrate is detected, and the detected foreign matter is analyzed using an analyzing technique such as laser photoluminescence or secondary X-ray analysis (XMR).
Moreover, disclosed as a technique for inspecting the presence of a foreign matter is a method for irradiating coherent light to a wafer, removing light, which is emitted from repetitive patterns on the wafer, using a spatial filter, and intensifying light reflected from a foreign matter or defect, which lacks repetitiveness, so as to detect the foreign matter or defect. Moreover, a foreign matter inspection system that irradiates light to a major group of straight lines, which is included in circuit patterns formed on a wafer, at an angle of 45°, for fear light having undergone zero-order diffraction due to the major group of straight lines may enter an aperture for an objective lens is described in Japanese Unexamined Patent Publication No. 1-117024 (Prior Art 3). In the Prior Art 3, a spatial filter is used to intercept light reflected from a group of straight lines other than the major group of straight lines.
As prior arts concerning a defect inspection system and method for inspecting a foreign matter or the like, methods described in Japanese Unexamined Patent Publications Nos. 1-250847 (Prior Art 4) and 2000-105203 (Prior Art 5) are known. In particular, as for the Prior Art 5, the patent publication describes that detective optical systems are switched in order to change detectable pixel sizes. As for technologies for measuring the size of a foreign matter, a method is disclosed in Japanese Unexamined Patent Publication No. 2001-60607 (Prior Art 6).